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ADAU1701 2nd order noise

Question asked by Ray.W on May 4, 2010
Latest reply on May 4, 2010 by JeradL

Hello

When I generated 2nd order high pass filter in SigmaStudio , the “Read back function block” showed output signal of RMS very huge. and I used a Audio Analyzer, output noise still very huge around 400~600uV, (normal noise showed around 12~14uV). Seems only 2nd order high pass filter abnormal.

Can you help?

 

There is my testing results in SigmaStudio:

  1. Bypass mode: Okay.
  2. 1st order High pass filter Okay.
  3. 2nd order High pass filter : NG, noise value showed 400~600uV.
  4. 1st order Low pass filter: Okay.
  5. 2nd order Low pass filter: Okay.

 

Test equipments:

Hardware : EVAL-ADAU1701 Rev.A ( Silicon Rev. ADAU1701 XSTZ#0605E)

Audio analyzer. (enable 20KHz LPF)

Software: SigmaStudio rev.3.1 build 9.

 

Ray.W

 

2nd_filter.bmp

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